What you need to know about fork oil.

[Garnet]

I have been attempting to dial in the forks on my CBR125R. Since there are few quality aftermarket bits out there for it I have had to learn to improvise. While looking for a blending formula to make up a custom viscosity, I came up with this site that has a ton of useful info fork oil and suspension fluid.

http://www.peterverdone.com/wiki/index. ... sion_Fluid

The big eye opener for me was the wild varying viscosity between brands. In other words, 5W, 7.5W, and 10W means very little.

Enjoy the read.

[Major Softie]

The big eye opener for me was the wild varying viscosity between brands. In other words, 5W, 7.5W, and 10W means very little.

Yes. I've been told before (I believe right here on this site) that this was impossible and I didn't know what I was talking about when I informed people about that.

Of course, the person delivering that message was probably one of those people we've been talking about how sad it is that they're gone....

[barryh]

Simple answer is to ignore the viscosity at 100 Deg C and only buy fork oil where they also list viscosity at 40 Deg C which is vastly closer to it's real in service operating temperature. The data can usually be found on the manufacturers web site.

For example, after much mucking about I know that I need oil that is approx. 28 cSt at 40 Deg C.
That for me is currently Castrol 5W synthetic which happens to be 5.7 cSt at 100 Deg C but the 5.7 figure is completely irrelevant outside of racing and maybe even then.

[Duane Ausherman]

Don't forget to experiment with the air above the oil, as it too is a spring.

[Garnet]

Don't forget to experiment with the air above the oil, as it too is a spring.

Yes, I am about to make my third and hopefully final adjustment to my air gap.